Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and a rotor having a rotatable hub and one or more rotor blades. The nacelle typically consists of a bedplate and a cover. The bedplate supports the generator, gearbox and other components located in the nacelle and transfers loads from the rotor to the tower. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, which is connected to the nacelle by a torque arm. The rotational energy is then transferred to the generator through the gearbox. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
Excessive noise generated by wind turbines is an ongoing concern, particularly in residential neighborhoods and areas surrounding a wind farm. A substantial contributor to wind turbine noise is vibrations induced in various components of the drive train and support structure. For example, in some instances, the gearbox creates strong vibrations that are subsequently transmitted to other components of the wind turbine, which may induce substantial noise. Thus, in many cases, a system commonly referred to as a tuned mass absorber (TMA) or tuned mass damper (TMD) is installed to reduce gearbox vibration.
Generally, TMAs are energy absorbing devices having a mass and one or more supporting rods mounted on a base structure. A TMA is typically mounted to a component of the wind turbine having a strong vibration under a certain frequency, such that energy is transferred from the component to the TMA. The highest energy transfer occurs when the natural frequency of the TMA is tuned to the natural frequency of the component. As such, typical TMAs operate efficiently only in a narrow band of frequencies, therefore, proper initial tuning and tuning maintenance are important design considerations for ensuring a properly working TMA.
Additionally, and as mentioned, TMAs are commonly installed on the torque arm of a gearbox of a wind turbine to reduce gearbox vibration. Although gearbox vibration at a particular frequency is a contributor to the noise issue, gearbox vibration is not a particularly “strong” contributor. On the other hand, bedplate vibration at generally the same frequency may excite structural components that are major radiators of overall noise, such as the tower or nacelle. Bedplate vibration typically results from the gearbox inducing such vibrations at a resonant or harmonic frequency. As such, bedplate vibration introduces component noise radiation and may cause more disturbing noise to neighboring areas in comparison to gearbox vibration.
Accordingly, an improved system for reducing vibrations in a wind turbine would be desired in the art. For example, a system for reducing vibrations in a wind turbine, wherein the system is located on the bedplate instead of the torque arm of the gearbox would be advantageous.